Abstract

This review summarizes current knowledge on both the most used photoinitiator system in dental resin (camphorquinone) and the alternative photoinitiator systems employed in dentistry. The review focuses on polymerization mechanisms, in vitro evaluation techniques, and factors that influence the degree of conversion and hardness of dental resin-based materials. A comprehensive electronic literature search was performed using PubMed, Google Scholar, and Elsevier databases, covering publications from 1984 to 2025. More than 30 articles were selected based on their relevance to the scope of this review. Light-activated dental resin-based composites (RBCs) represent the most widely used restorative materials in clinical practice. However, effective polymerization of each photoinitiator system depends on the use of a compatible light-curing unit with an appropriate emission spectrum. Changes in the photoinitiator system can markedly affect the biomechanical properties of dental resins, including degree of conversion, hardness, and biocompatibility. This review provides a comparative analysis of RBCs formulated with different photoinitiators, such as camphorquinone, benzophenone, 1-phenyl-1,2-propanedione, trimethylbenzoyl-diphenylphosphine oxide, and benzoyl peroxide. The main objective of this article was to highlight alternative photoinitiators capable of overcoming the color drawbacks of camphorquinone, particularly yellow discoloration, while maintaining comparable mechanical performance. Although current evidence suggests that no alternative photoinitiator fully matches the effectiveness of camphorquinone, certain systems—such as benzoyl germanium derivatives and novel acylphosphine oxide photoinitiators used in combination with camphorquinone—appear promising for enhancing esthetic properties and increasing the degree of conversion of dental RBCs.

Key Points